In order to extract oil and gas from geological formations it is known to pump well treatment fluids into wells. One known process of extraction is hydraulic fracturing, also known as fracing. In the fracing process a well treatment fluid is pumped through a well bore hole into a geological formation at a pressure which causes the creation and opening up of fractures in the geological formation.
Well treatment fluids are typically pumped into wells at high pressures and with high flow rates. As a well treatment fluid is pumped through a well it experiences friction. For example, friction is produced due to the interaction between the fluid and the well bore lining and by turbulent flow. Such friction means that greater energy must be used to pump the fluid than would be required to pump the same amount of fluid at the same flow rate in the absence of such friction.
In order to reduce friction it is known to add friction reducers to well treatment fluids. Typically, well treatment fluids comprise an aqueous fluid to which a polymeric friction reducer is added. US2010/0200239 describes the use of a combination of polymeric friction reducer and 3,5-dimethyl-1,3,5-thiadiazinane-2-thione in a well treatment fluid.
Although well treatment fluids comprising friction reducers are known there remains a need for improved well treatment fluids and friction reducers. Accordingly, the present invention aims to address at least one disadvantage associated with the prior art whether discussed herein or otherwise.